The present invention relates to an improved heating or air-conditioning system for vehicles which has a cold-air duct and a warm-air duct which open out into an air-mixing chamber. A first control member, assigned to the cold-air duct, sets the amount of cold air which flows into the air-mixing chamber, and a second control member, assigned to the warm-air duct, sets the amount of warm air which flows into the chamber. The second control member is designed as a shutter having a plurality of pivotable closure lamellae which are arranged next to one another, overlap one another in the closed position, and can be pivoted by a common actuating drive.
In a known air-conditioning system of this type (DE 41 19 474 C2), both the cold-air control member and the warm-air control member are designed as shutters. In each case, two-winged closure lamellae can pivot about one centrally arranged pivot axis. To close off and to partially or completely open up the associated duct cross section, the closure lamellae are simultaneously pivoted through the same pivot angle.
Such shutters may be used in air-controlled air-conditioning systems, in which the desired compartment temperature in the passenger cell is set exclusively by mixing suitable amounts of warm air and cold air at the heat exchanger which is constantly heated by the cooling water of the internal-combustion engine. When the shutters are used in such air-conditioning systems, it has been found that, in the lower control range of the air temperature, the control curve is excessively progressive, i.e. the amount of warm air which flows into the air-mixing chamber is too high in the range of small opening angles of the closure lamellae.
One object of the present invention is to achieve a more linear control curve of the mixed-air temperature or of the amount of warm air flowing into the air-mixing chamber in a heating or air-conditioning system of the type described above. It is also an object of the invention to achieve this more linear control with the actuating travel of the common actuating drive for the closure lamellae by suitably designing the shutter for the warm-air duct.
According to the invention, the object is achieved by having the individual closure lamellae, when they are pivoted out of their closed positions, open up unevenly sized opening cross sections for the warm air to pass through. The sum of the unevenly sized opening cross section is such that a predetermined amount of warm air is fed to the air-mixing chamber as a function of the actuating travel of the actuating drive.
The heating or air-conditioning system according to the invention has the advantage that a linear or any other desired control curve can be achieved for the mixed-air temperature by suitably influencing the pivoting travel of the closure lamellae. In this way, it is possible to accurately adapt the control curve, particularly in the lower temperature range. Moreover, by differently setting the opening cross sections which are opened up by the individual closure lamellae, the flow of air into the air-mixing chamber is also optimized, so that the mixing of cold air and warm air is improved.
Advantageous embodiments of the heating or air-conditioning system according to the invention, with expedient refinements and configurations of the invention, are further reflected in the claims.
According to one advantageous embodiment of the invention, the closure lamellae are coupled to the actuating drive in such a manner that, for the same actuating travel, they rotate through different pivoting angles. In this case, the closure lamellae are preferably coupled to the pivoting drive in such a way that, with increasing distance of the closure lamellae from the cold-air duct opening in the airmixing chamber, the pivoting angle of the lamellae decreases for the same actuating travel of the actuating drive. The closure lamellae may be of one-winged or two-winged design, with the pivot axes being arranged at the edge or in the center of the lamellae.
In an alternative embodiment of the invention, the closure lamellae are coupled to the actuating drive in such a manner that they are pivoted successively. In this case, the pivoting operation of a following closure lamellae commences after the end of the pivoting operation of the preceding closure lamellae.
According to one preferred embodiment of the invention, the closure lamellae are pivotable about a centrally arranged pivot axis, and a curved blocking surface is fixed to the duct wall, concentrically with respect to the pivot axis of at least one outer closure lamellae which is next to the duct wall. The edge of that wing of the outer closure lamellae which faces towards the duct wall is sealed against this blocking surface. In this case, the blocking surface extends, starting from the closed position of the outer closure lamellae, over a predetermined partial pivoting travel of this lamellae. By providing a design of this type, it is possible to influence the control curve of the shutter using little manufacturing outlay. Compared to conventional shutters, it is only necessary to alter the housing moulds and, if the blocking surface is formed on a frame which holds the closure lamellae and is fitted into the duct, the frame moulds. There is no additional outlay on parts.
According to one advantageous embodiment of the invention, the shutter has at least three closure lamellae and each wing of the two outer closure lamellae which faces towards the duct wall is assigned a blocking surface. In this way, the opening cross section of the shutter in the lower control range can be set even more finely.
The invention is described in more detail below with reference to exemplary embodiments illustrated in the drawings.